This project seeks to use genetic, biochemical and physiological approaches to investigate the oral bacteria. Three specific areas of investigations are: A) the use of molecular biological techniques to characterize surface antigens of oral microbes; B) the characterization of plasmids isolated from oral bacteria and C) the study of the regulation of sugar transport systems. A 'genomic library' of Actinomyces viscosus DNA was prepared in Escherichia coli using the cosmid vector pHC79. The library was screened for expression of A. viscosus antigens using immunological techniques. One clone was found that produced a subunit of the Type 2 fimbriae. Western blot analysis has confirmed that this clone produces a protein indistinguishable from a component of the Type 2 fimbriae. The gene has been further subcloned into pUC13 on a 4.3 Kbp Bam fragment and found to produced a truncate 30 Kalton product. Lactose plasmids isolate from strains of L. casei encode the membrane associate lactose transport system (lac-PTS) and the soluble enzyme, phospho-Beta-galactosiase. The plasmids vary in size and restriction enzyme cutting patterns. Southern blots demonstrate that they represent a series of different plasmis carrying homologous lac genes. The multicopy cryptic plasmids were characterized by restriction endonuclease mapping, cloning into E. coli an minicell analysis. Shuttle vectors capable of replicating in E. coli or S. sanguis and L. casei were constructed. Methods for the efficient production and regeneration of L. casei protoplasts have allowed the introduction of DNA into Lactobacillus strains for the first time via a highly efficient liposome-mediate transfection system (105 transfectants/ ug DNA). A hexose 6-phosphate phosphohydrolase was purified and characterized. Lactose analogs were synthesized enzymatically and used to produce high intracellular 2-DG and 2-FG system in studies of the effect of intracellular glucose concentrations and the glucose efflux system. First evidence was obtained for the intracellular phosphorylation of glucose and glucose analogs by the glucose-PTS.